Why are Buchanan and Harding consistently ranked as the worst Presidents?

Buchanan basically dithered while the South got organized before the civil war at a time where strong leadership could have been effective. That makes sense.

Harding though ran on staying out of the League of Nations, Organized the Washington Naval Conference, pardoned Eugene Debs and released political prisoners. Teapot Dome was bad, but it was a cabinet scandal that he wasn’t involved with, and his affair while bad seems comparable to Cleveland or Wilson who both had sex adjacent scandals in recent history. He died before most of the scandals came out, but by all accounts had great cabinet and court appointments. Mid I can understand, but why is he constantly considered one of the worst? Thanks!